1. Field of the Invention
This invention relates to an apparatus for processing an exposed roll of instant or self-developing type film so as to initiate the formation of a visible image therein.
2. Description of the Prior Art
The present invention relates to apparatus for processing an exposed roll of 35 mm film, preferably of the instant or self-developing type transparency film, and more particularly to an improved drive train for rotating various members of the processing apparatus. The apparatus is compact, inexpensive, easy to use and is especially attractive to the photographer who desires to process his own film.
An example of a processing apparatus of the general type described above may be found in U.S. Pat. No. 4,370,045. This apparatus includes first and second drive spindles which are adapted to (1) rotatably support a film spool and a sheet material spool, respectively, during an early film processing phase in which sheet material and film are being unwound from their respective spools, and (2) drive or rotate the spools during a latter processing phase so as to rewind the film and sheet material upon their respective spools. The apparatus also includes a manually operative lever for moving gears into and out of a gear train, depending upon which processing phase is to take place next, and a hand crank for driving various elements of the processor. Such an arrangement involves more than a small amount of engineering acumen to insure the proper movement and meshing of the gears as well as the full attention of the operator of the processor when he is moving the aforementioned lever between its two operative positions. Should the lever be in the wrong position during initial rotation of the crank, the photographically exposed film will be withdrawn from its cassette and then rewound into the cassette with any processing liquid being applied thereto. Thus, when the operator removes the film cassette at the end of the "processing phase" (which didn't occur) and withdraws the film from the cassette it will be further exposed by the ambient light. Also, if the mechanism for shifting the gears is in the wrong position when a processing kit is loaded into the processor and the loading door shut, it, the loading door, may be inadvertently locked in the closed position and a special tool may be needed to unlock the loading door. Still further, if the operator were to now move the lever into its other position, it is possible that the processing kit may be broken by the processor's pod breaking roller since the housing of the kit will be in a closed position.
A motorized version of a film processor of the type under discussion is shown in U.S. Pat. No. 4,537,485. This processor does address itself to some of the problems described above with reference to the '045 processor. However, the '485 processor includes a drive system in which a one-way clutch is located between a sheet material spindle and a motor, and between a film spindle and the motor. It appears that these one-way clutches allow the film spindle and the sheet material spindle to freely rotate during the winding of the film and sheet material upon a winding shaft, thus possibly leading to a condition wherein a greater amount of either, or both, of the film and the sheet material is being unwound from its respective spool, vis-a-vis, the amount being wound upon the winding shaft. Further, the '485 processor does not appear to have any structure whereby slack in the length of the film (leader) between its cassette and its point of attachment to the processor's winding shaft can be removed without also increasing the tautness of the web of sheet material.
Still another film processor similar to that shown in the '045 patent is the AutoProcessor, sold by Polaroid Corporation of Cambridge, Mass. As diagrammatically depicted in FIG. 4 of the present application, this processor includes a drive train which comprises structure for removing slack in the film leader during loading without materially affecting the tautness in the underlying length of sheet material. However, it does suffer the aforementioned disadvantages of having a drive system wherein various elements are manually moved into and out of the drive system during different phases of the processing cycle.